My combination dust extractor and support plate for table mounted routers, relates generally to dust extraction systems for shop woodworking tools. More specifically, the invention relates to dust extraction systems and support plates for use with table mounted woodworking routers.
A router is a woodworking power tool utilizing a high speed cutting bit to trim and shape a workpiece. In its basic form, the router is used as a hand-held tool in a vertical position with the bit downward, shaping a stationary workpiece. A router may also be mounted in an inverted position for table or bench use. In this application, the router is mounted to a support plate, which allows the router and attached support plate to be set into a recess in a work table with the bit protruding above the table top. This allows the workpiece to be passed over the stationary router, rather than passing the router over a stationary workpiece.
The conventional router support plate is a simple rectangular plate of solid metal, wood, or plastic. The router is attached under this plate, which has a hole at its center through which the router bit protrudes upward. The only purpose of this support plate has been to support the router beneath the work table. The support plate is often of a universal design, allowing attachment of various router models by drilling through the plate in a pattern to match the specific routers dimensions.
One characteristic typical of all woodworking routers is the large amount of waste wood dust and particles generated during operation. Collecting and extracting this waste material has been a continuing problem, and prior art systems designed to do so have not been totally successful.
Prior art router dust extraction systems for table mounted routers are of three types:                a) systems mounted above the router table that comprise a fence or other device with a hollow chamber and an opening near the router bit. When a vacuum source is attached to the hollow chamber, dust generated during router operation can be extracted from above the table.        b) systems that comprise a dust cup which attaches beneath the router table or support plate, directly under the router bit opening. When a vacuum source is attached to the dust cup, dust can be extracted from the router bit opening. A variation of this type comprises an enclosure which surrounds the router. When a vacuum source is attached to the enclosure, negative pressure within the enclosure pulls dust from the router bit opening into the attached vacuum source.        c) a combination of systems (a) and (b).        
Prior art dust extraction systems designed to extract dust from above the router table (type (a) described above) are ineffective when the workpiece covers the router bit and bit opening, such as when making a dado cut. In this mode of operation, above-table extraction systems have no means for collecting dust because the router bit, and therefore all generated dust, is isolated from the extraction system. Also, above-table systems require hardware and a vacuum hose mounted on the work table surface which can interfere with router operation.
Prior art systems designed to extract wood dust from below the router table (type (b) described above) are capable of extracting dust generated while making dado cuts, but suffer from other deficiencies. These systems limit vertical travel of the router, making above-table bit changing difficult or impossible; impede ventilation air flow from the router motor, thus risking overheating of motor; and the crowding of a vacuum hose and dust cup between the router motor and bit opening is an awkward arrangement. Some below-table systems are of proprietary design thus not universally adaptable to all woodworking routers. Location of the dust cup compromises dust extraction effectiveness because the suction is remote from the router bit, also suction is partially obstructed by the bottom of the router support plate.
Prior art systems comprising a combination of above-table and below-table extraction systems (type (c) described above) exhibit many of the problems that are present in their specific types. In addition, these “combination” extraction systems are more complex due to additional equipment installed above, below, and around the router, thus interfering with router operation. Combination systems often require larger non-standard vacuum systems. Although there have been many dust extraction systems developed and marketed for woodworking routers used as hand-held tools, fewer systems have been developed specifically for table mounted routers. Relevant examples of prior art systems designed to extract dust from woodworking routers include the following:
U.S. Pat. No. 4,051,880 (Hestily) discloses a hand-held router combined with a dust collection feature, not a dust collection system for table mounted routers. It consists of a portable electric router having a dust chamber formed below a motor mounted to a base having two handles one of which connects the chamber to a blower and dust bag fixed to the top of the motor. Additionally, the device described is a proprietary router and not for use with conventional routers, thus is not adaptable to existing routers.
U.S. Pat. No. 4,738,571 (Olson et al.) discloses a system intended for the collection of dust from a hand-held router. It consists of a base with a dust port, a sub-base having a large cavity attached to the base, with both attached to a router. While this apparatus conceivably could be attached to the underside of a work table, it appears that the small hole in the base will limit the depth of some cuts, as collets of routers will not pass through it. In addition, provisions are not evident for the large variety of different dimension router bases that are currently in production, therefore this system would not be universally adaptable.
U.S. Pat. No. 5,553,644 (Adams) is a system intended for a table-mounted router, and comprises a fence of hollow rectangular configuration defining a chamber that is connectable to a vacuum source for removal of dust produced by a cutting tool such as a router. The system appears to be adaptable to a variety of router tables but is capable of collecting dust from only the top of the table surface, thus has the characteristics of type (a) above. It does not have any means for collecting dust from below the router table, therefore ineffective when the workpiece covers the router bit and bit opening, such as when making a dado cut.
U.S. Pat. No. 5,611,378 (Brazell) discloses a router table assembly with a tiltable table subassembly that allows variation in positioning the router and includes a router mounting plate specifically designed for the table and a unique table design. The table and mounting plate include vacuum channels with a tube connectable to a vacuum source. The design of the channels is such that slivers of wood are likely to clog the dust escape route and render the system inoperable. Aside from this issue, the channels do not appear to be of sufficient height to accommodate many of the mid and larger size cutting tools that are currently on the market. An additional limitation is the fact that the dust collection system is built into the table and is not adaptable to the many other router tables and router support plates currently on the market, thus is not a universal fit.
U.S. Pat. No. 5,993,124 (Cooper) describes a system that includes a router sub-base adapted for connection to a hand-held router. The system includes lower and upper vacuum flow paths configured to evacuate dust from within and beneath the router sub-base. This system is designed for cutting edges of work pieces by hand and not for use with a table mounted router, nor is it attachable to a router table. The design is such that wood dust is collected to the rear side of the router away from the cutting tool, with dust and particles likely escaping from the front side of the cutting operation. There is no provision to collect dust coming from this area. In addition, with this system installed on a router, dust collection will not be possible for dado types of cuts and it is not a universal fit for routers.
United States Patent Application 2010/0089497 (Keenan) discloses a dust collector for use with table mounted routers. The system includes both above-table and below-table dust collection devices, therefore is a system with the characteristics of type (c) described above. This dust collector system includes a flexible cup device attachable to the underside of the router table, with a hose opening on the cup connectable to a shop vacuum. Users of collection systems which incorporate similar devices report several problems with these “dust cups”. They find it necessary to remove the dust cup in order to change router bits; they encounter difficulty keeping the dust cup and attached hose connected beneath the router; they find that particles can plug the opening to the vacuum hose; and they find that setup time is lengthy. The system also includes a fence with a dust port opening, also connected to the shop vacuum. This system, and others of similar design, are unnecessarily complex and require multiple vacuum hoses which can interfere with the router operation. A larger non-standard shop vacuum system is often required for this type system.
Therefore, a need exists to provide a waste dust extraction system that is adaptable to any conventional woodworking router when used in table mounted operation; which can be operated in combination with a standard shop vacuum; is effective in extracting dust produced in any routing operation, and does not interfere with router operation or router bit changing. There is further need for an uncomplicated stand-alone system which does not require additional extraneous dust extraction equipment.